Typical current motor protection circuit breakers, for rated currents up to approximately one hundred amperes, are designed with bimetal strips/heaters for thermal protection and magnetic plungers for short circuit protection. The operation of these devices produces a significant amount of power loss in the form of heat. The trend of government regulation and public opinion is towards a reduction in power consumption of all electrical devices, creating market pressure for more efficient electrical device designs. Further, reduced operating expenses are available to encourage the use of the design in new applications and to offset the cost of retrofitting existing applications with a more efficient circuit breaker.
Another shortcoming in the design of this class of conventional circuit breakers is the lack of integrated electronics for measuring circuit breaker conditions and the ability to communicate this data to a control system or network. Greater efficiency of operation and preventative maintenance opportunities are lost because the first sign of a problem with the circuit breaker is after the circuit breaker failure. Further, a high form factor with regard to the design's operational characteristics in this class of circuit breaker, such as speed of contact opening, prevention from reclosing, and/or prevention from welding, leads to higher manufacturing cost. Furthermore, the design of this class of conventional circuit breakers has a large size. In addition, in conventional designs, an excessive amount of magnetic flux is shunted away, which leads to a high level of breaker trip current and severely compromises the trip function of the circuit breaker. Moreover, the poor magnetic coupling can result in low transformation efficiencies, low secondary output current, and/or loss of current measurement linearity.